Cassandra Ridder was crushed when her 12-year-old son Brody came home from school recently with only a few signatures in his yearbook — including his own.

"Hope you make some more friends. - Brody Ridder," the rising seventh-grader wrote in his own yearbook, which was signed by only two classmates, two teachers and himself.

"It broke my heart," Ridder said.

Brody has been a student at the Academy of Charter Schools in Westminster, Colo., a public prekindergarten-to-grade-12 school, since fifth grade. He had several friends at his previous school, but over the past two years, he has struggled socially and has been repeatedly bullied, his mother said.

"There's kids that have pushed him and called him names," said Ridder, adding that she decided to switch her son's school before fifth grade to give him more academic support. "Brody has been through a lot."

Although the bullying somewhat subsided after she addressed her concerns with school administrators in February, she could tell "the teasing was still there," Ridder said.

When Brody asked his classmates to sign his yearbook on May 24, "they told me no," he said in a phone interview with The Washington Post. "It made me sad."

"We try to teach kindness in our family, and not seeing any kindness from students in his class was appalling to me," Ridder said.

She shared a photo of her son's yearbook note in a private Facebook group for parents at the school. She felt angry and helpless, and while she did not ask for her son's permission before posting, "I knew he would be completely OK with it," she said. "Brody has always told me he wants to be part of the solution."

Her primary objective in posting the photo, Ridder explained, was to encourage parents to talk to their children about bullying. She said she's aware that some parents prefer to keep such matters private, but she thought that being forthright about it might help prevent her son and others from being targeted further.

She hoped people would sympathize with her son's struggle, but she did not anticipate the outpouring of support that swiftly surfaced after her post — particularly from older students at the school.

As dozens of compassionate comments poured in, several older students — none of whom previously knew Brody — heard about Ridder's post from their parents. They stepped up to show their support.

Cooper remembers being Brody's age, and the intense pressure she felt to fit in. Having signatures in your yearbook wasn't only a measure of popularity, she recalled, it also meant simply "knowing that you have friends."

"Signing someone's yearbook was all the rage," she said. "That people would tell him no and deny him a signature, it just hurt my heart."

She contacted several friends and they coordinated to visit Brody's homeroom class together the following day. Little did she know at the time, but many other students were hatching the same plan.

When Simone Lightfoot, also an 11th-grader at the school, saw Ridder's post, her first thought was: "I'll get some of my friends and we'll go sign it," she said.

Lightfoot, 17, could relate to Brody's plight.

Maya Gregory, an eighth-grader at the school, felt likewise. She, too, was bullied at Brody's age.

"No one helped me when I was in that situation," said Maya, 14. "So I wanted to be there for him."

She rounded up her friends, all of whom were eager to give Brody a confidence boost. The impromptu initiative spread throughout the school, and on May 25, the day after the yearbooks were distributed, a swarm of older students filed into Brody's sixth-grade classroom, ready to sign his yearbook.

Although he felt shy at first, "it made me feel better," said Brody, adding that he collected more than 100 signatures and messages of support in his yearbook that day. He also got some phone numbers and a gift bag.

"Just seeing him light up, it felt really good," said Cooper, who is hoping to spearhead a schoolwide yearbook signing next year to ensure that this doesn't happen to another child. "It was a small thing, but it made him so happy."

As upperclassmen filled the pages of Brody's book, several of his classmates got up from their seats and signed their names, too.

"It really showed us that coming in to make his day was already having an impact on the people in his class," Cooper said.

She and her friends didn't just sign Brody's yearbook; they also made an effort to get to know him, and asked about his hobbies — including chess and fencing. Then, they gave him a pep talk, since many of them were once in his shoes, they told him.

"It made me feel like I was not alone," Brody said.

Maya, for her part, promised Brody that beyond signing his yearbook, she would continue to be there for him. She gave him her phone number, and they have already met for ice cream with a few of her friends. They bonded over their shared experience with bullies, and she imparted words of wisdom: "Whoever is trying to bring you down is already below you," she told Brody.

"A lot of students are struggling with peer relationships and social skills," said Brent Reckman, chief executive at the Academy of Charter Schools. "It's up to us to figure out how to help kids and families with it, but it's a challenge faced by all schools right now."

"It can be really tough to be a teenager," he continued. "I was really impressed with how our students stepped up when they saw a peer in need."

Ridder echoed his sentiment. While she never predicted her candid post would yield such a meaningful outcome for her son, she's very grateful that it did.

"It made me feel like there's still hope," she said. "Not just for Brody, but for humanity."